ABSTRACT
The phylogenetic position of brachiopods within the Metazoa is a matter of ongoing debate. Morphological analyses clearly place the Brachiopoda within the deuterostomes (Eernisse et al., 1992; Nielsen et al., 1996) while molecular analyses consistently reveal a protostome affinity (Halanych et al., 1995; Cohen et al., 1998; Erber et al., 1998; de Rosa et al., 1999; Stechmann and Schlegel, 1999). Moreover, it could be shown that brachiopods branch off, together with the remaining lophophorates (phoronids and bryozoans), in a cluster with molluscs and annelids. As this clade groups lophophorates and eutrochozoan taxa it was designated Lophotrochozoa (Halanych et al., 1995). These findings were confirmed by mitochondrial gene order comparisons and amino acid sequence analyses, using the complete mitochondrial genome of the brachiopod Terebratulina retusa (Stechmann and Schlegel, 1999). Despite the number of molecular studies carried out to date, the branching order within the Lophotrochozoa remained elusive.
